A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

Questions regarding large spheres of plasma undergoing fusion.
Questions regarding the closest star to Earth, at the centre of the Solar System.
Questions regarding points of extremely high mass density, which creates an extremely strong gravitational field from which light cannot escape.
Questions regarding an object 'falling around' another object, due to a combination of gravity and momentum.
531 questions
Questions about the techniques and practice of observing the night sky.
Questions on astronomical objects orbiting a star massive enough to be rounded, not massive enough to cause fusion, and which have cleared its orbit of planetesimals.
Questions regarding Earth's only natural satellite. For questions about the natural satellites of other planets, use the tag [natural-satellite].
Questions regarding systems of large numbers of stars held together by gravity.
Questions regarding the Sun and objects orbiting it.
Questions regarding the attractive force which exists between any two bodies of matter.
424 questions
Questions related to the physical instruments for astronomical observations.
416 questions
Questions regarding the planet on which humans live; the third planet from the Sun.
410 questions
Questions involving the physics of the universe, especially the nature of astronomical objects, energy fields, and/or regions, rather than their positions or motions in space.
Questions about the observation of celestial objects by non-professional astronomers.
312 questions
Questions regarding planets that lie outside the Solar System.
Questions about the origin, history, evolution and fate of the Universe.
290 questions
Questions regarding all of time and space and its contents.
278 questions
Questions regarding electromagnetic radiation in the visible spectrum.
262 questions
Questions regarding relatively small rocky bodies in an orbit around the Sun.
223 questions
Questions regarding the amount of space between two objects, the units, or measurement thereof.
202 questions
Questions regarding the Milky Way Galaxy, the galaxy that Earth's solar system is in.
182 questions
Questions about observation performed in the radio frequency range of the electromagnetic spectrum (between 10 MHz and 100 GHz).
174 questions
Questions regarding the 4-dimensional background structure of our universe.
166 questions
Questions about photography of celestial objects by amateur or professional astronomers. Questions about photography of other objects are off-topic but might be asked on our sister site Photography St…
165 questions
Questions on systems to uniquely determine position of a point or other geometric element on a manifold such as Euclidean space.
Questions regarding stars which increase suddenly in energy output due to an explosion which ejected much of its mass.
156 questions
Questions involving reference frames, time scales, and how they are determined.
154 questions
Questions regarding the action of or an object rotating along an axis.
149 questions
Questions regarding a layer of gasses surrounding a celestial object.
147 questions
Questions about the increase with time of distance between two distant points in the Universe.
147 questions
Questions about relativistic theory of gravity. General relativity describes gravity as a geometrical property of space and time.
147 questions
The near-vacuum extending between the planets and stars, containing small amounts of gas and dust. Also called outer space to refer to the physical universe beyond the Earth's atmosphere.
145 questions
Questions regarding the currently prevalent cosmological model for the origin of the universe.
142 questions
Questions regarding Mars, the fourth planet from the Sun.
141 questions
Questions regarding Jupiter, the 5th and largest planet in the Solar System.
141 questions
Questions on celestial bodies that orbit planets.
136 questions
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